/Engine/Source/Runtime/GeometryCore/Public/DynamicMesh/DynamicMesh3.h
Compute triangle normal, area, and centroid all at once. Re-uses vertex lookups and computes normal & area simultaneously.Howeverdoes not produce the same normal/area as separate calls, because of this.
void GetTriInfo ( int TriangleID, FVector3d & Normal, double & Area, FVector3d & Centroid ) const